The invention relates to a process for the production of outer attachment faces on joint implants made from a plastically deformable metal, whereby the attachment faces are at an angle .alpha. of between 0 and 90 degrees to an insertion and attachment direction of the joint implant.
Joint implants have to absorb forces on their attachment faces to the osseous tissue in various directions. The attachment faces should therefore be able to transmit forces in the greatest possible number of directions, without a loosening of the implant occurring. As a result various textures for implant faces have been developed. Thus European patent publication 186,471 shows a knee joint prosthesis having grooves similar to saw teeth, which are mounted transversely to the insertion direction, whereby the stability in the direction of the grooves is reduced. A further alternative specifies pins similar to barbs at the prosthesis, which penetrate the femur stump in the insertion direction. A general requirement for attachment faces of this type is that they should firstly comprise a structure promoting ingrowth and that secondly they should be economical to manufacture. German patent publication 2,914,513 shows attachment faces which are provided with nipple-like protrusions and indentations in order to improve ingrowth. No statements on the production and absolute dimensions of this structure were given. In the relative geometrical conditions shapes rounded on all sides are proposed, which only permit a limited primary attachment. A further structure is proposed in European patent publication 381,351, in which at a hip joint shell on an outwardly protruding boss a type of knurled attachment face with flattened protruding pyramids is produced by recesses, which extend obliquely to the equator and are offset in the peripheral direction, and which cross. Here too the primary attachment is restricted, i.e. is very much dependent on the prestressing in the bone cavity and respectively on the undersize of the bone cavity in the region of the equator.